Three new species of Celastraceae from Costa Rica, one disjunct from Mexico

This paper was reviewed and accepted in November of 1996 for publication in Novon, Vol. 7 (2). In preparation for and in keeping with the theme of electronic distribution of the
Manual to the Plants of Costa Rica, the mss. was made available on two Web sites (INBio and MO) by 14 April 1997.

Abstract. Three species of Celastraceae, each represented by many collections from Costa Rica, are compared to near relatives and found to be new: Gymnosporia haberiana Hammel, disjunct from Mexico and Costa Rica, Maytenus recondita Hammel, of Costa Rica and Panama, and Crossopetalum enervium Hammel, of Costa Rica . The South American Gymnosporia magnifolia (Loesener) Lundell is here confirmed as a synonym of G. urbaniana (Loesener) Liesner, and Crossopetalum eucymosum (Loesener & Pitter) Lundell is placed in synonymy under C. parviflorum (Hemsley) Lundell. Keys are provided for all accepted neotropical species of Gymnosporia, and for all Costa Rican species of Crossopetalum and Maytenus.

For nearly twenty years collections of two large, cloud forest trees
in the family Celastraceae have been accumulating, primarily from the
Monteverde region of Costa Rica. Much of this material has been
distributed to various herbaria under tentative or approximate names.
More recent exploration along the central cordillera has extended the
range, within Costa Rica, of these two species and yielded many
collections of a third, shrubby species in the genus
Crossopetalum, also known from the Monteverde region. The two
trees are known almost exclusively from mid-elevations on the Pacific
slopes of the northern mountains, while the shrub extends nearly the
entire length of the country and is known from numerous collections
on both slopes.

Although one of the trees has always been known to be a Maytenus presumably related to M. schippii Lundell, generic placement of the other has been more problematic. This species, while having alternate leaves and capsulate fruits with arillate seeds, as in Maytenus, has greener drying, entire leaves, more open and branched inflorescences with 4-merous flowers,
and several seeded, 2--4 lobed fruits. In these respects the Costa Rican (and Mexican) tree can be distinguished from other alternate-leaved Celastraceae and coincides perfectly with two South American species recently described in or transferred to the genus Gymnosporia (Lundell, 1985; Liesner, 1993).

Distribution and biogeography. Gymnosporia haberiana is disjunct between one site at about 300 m elevation in Veracruz, México, and several wet-forest, mid-elevation sites in NW Costa Rica (Fig. 2). However, its nearest
relatives, as discussed below, are from low- and mid-elevation South America, a common pattern for tropical Mexican and Central American taxa (eg., Hammel, 1986 and references therein). Nevertheless, G. haberiana is not known from southern Costa Rica or from Panama. This disjunct distribution
between Mexico (or northern Central America) and Costa Rica, then skipping Panama to nearest relatives in South America, is not unique (eg. Ziziphus chloroxylon (L.) Oliv.), and if not an artifact of collecting, may itself reflect the complex geological history of the isthmian region.

Relationships. The closest relatives of Gymnosporiahaberiana are its two South American congeners. In 1985
Lundell transferred Maytenusmagnifolia Loesener to
Gymnosporia and described a second neotropical species,
G.gentryi Lundell, thus reinstating for the New World
an essentially African genus that had come to be considered
congeneric with Maytenus. In contrast to species of
Maytenus, most of which (at least in the neotropics) have
small fasciculate inflorescences, 5-merous flowers, 1 or rarely
2-seeded fruits, and often toothed, gray- or tan-drying leaves, the
New World Gymnosporia have relatively large, open cymose
inflorescences, 4-merous flowers, usually 2--4-seeded fruits, and
entire, greenish-drying leaves (see also Hou,
1955). Study of specimens and bibliographic
material at MO supports Liesner's conjecture
(1993) that G.urbaniana (the
older name) and G.magnifolia are conspecific:

The new species differs from G. gentryi of Colombia
and Ecuador and G. urbaniana of Amazonian Brazil, Peru
and Bolivia by its generally smaller leaves with less conspicuous
lateral veins, usually fewer-flowered inflorescences, and sepals that
are much broader than long. Gymnosporiaurbaniana has
smaller flowers with almost no nectar disk and is found mostly in
lowland Amazonia. Gymnosporiagentryi, from 1200--2800
m in the northern Andes, has flowers nearly as large as those of
G.haberiana, but the ovary (and fruit) is distinctly
4-angled and its leaves have very prominent (below) lateral veins
that depart from the midrib at a much narrower angle. By these
observations, G. haberiana and G. gentryi
appear to be sister species. The three neotropical species of
Gymnosporia can be separated according to the following
key:

Mexican material of this species has sometimes been tentatively
identified as Maytenus grisea Lundell, but examination
of the Guatemalan type of that species (Contreras6944,
LL!) shows G. haberiana to be quite distinct. Although
the two species are superficially similar because of their somewhat
inflated and relatively thin-walled fruits, in contrast to the open
cymes and lobed fruits of G. haberiana, the
inflorescences of M. grisea are only pedicellate
clusters on a very short or obsolete peduncle, the fruits are not
lobed, and the leaves are toothed and dry gray rather than green.
Unexpectedly, this study has revealed that a rarely collected Costa
Rican plant from hills near Palmar Norte (Allen 6327, F
[as "Maytenus pallidifolius Standl. & L. O. Williams ined."];
Bohlke 20, F; Hammel et al. 20296, INB; Poveda & Hoet 3050, CR) is certainly
conspecific with M. grisea. Thus, M.
grisea, known only from the type in Guatemala and now from
southern Costa Rica (Fig. 2), is similar to
G. haberiana in being disjunct within the region.

Etymology and history. This new species is dedicated to my
friend and colleague, Dr. William Haber, long-time student and
professor of the rich flora of Monteverde, Costa Rica, locality of
the type and most other collections cited here. Bill's keen
observation and field notes brought to my attention the dioecious
nature of this species. The earliest known collection of this species
is from Mexico (Cedillo436, Nov 1974). In Costa Rica
it was apparently first collected in Jul 1977 (Dryer1589).

Distribution. Except for one sterile collection from western
Panama, Maytenusrecondita is restricted to wet forests
of central Costa Rica (Fig. 2), primarily at
700--1700 m elevation on the Pacific slope from the Cordillera de
Guanacaste to the Cordillera Central, with one low-elevation,
Atlantic-slope collection from the Río Barbilla region,
Cordillera de Talamanca, (Herrera2278) and another
isolated collection from the Osa Peninsula (Aguilar4524).

Characterization. This species is recognized by the acuminate
and decurrent, gray-green drying leaves and the paniculate
inflorescence of reduced or aborted cymes. It is generally a larger
tree as compared to M.segoviarum Standl. &
Steyerm., with which it is sympatric in Costa Rica. It has been
identified in the past as M.schippii Lundell "vel. sp.
aff.," but differs from M. schippii by its shorter
petioles, branched, pedunculate (rather than fasciculate)
inflorescences, and higher-elevation habitat. Another similar
species, currently identified in Costa Rica as M.
guyanensis Klotzsch ex Reissek, differs by its much larger,
usually darker drying leaves, fasciculate inflorescences, and
lower-elevation habitat. The five species of Maytenus
recognized for Costa Rica can be distinguished by the following
key:

Anthers on flowering material of M. recondita also
bearing young fruits appear (on close examination) not to bear
pollen. Although the relative length of stamens and style does not
differ strikingly in staminate and pistillate flowers, as in the
above-discussed species of Gymnosporia, M.recondita must also be dioecious.

A series of collections from Costa Rica (U.
Chavarría179, INB; Chávez248, INB; Ezpinoza 1186, INB; G.
Herrera 850, INB; A. Rodríguez188, INB) is here specifically excluded from the concept of
M. recondita. This entity shares the elevational range,
inflorescence type, and leaf color of M. segoviarum,
but has a leaf shape more similar to that of M.
recondita. It is not yet decided whether these collections
represent a sixth species for Costa Rica, hybrids between M.
recondita and M. segoviarum, or simply variation
within M. segoviarum.

Etymology and history. The epithet recondita ("hidden,
unpretentious") was chosen for this species because its primary
distinction is its reduced but nevertheless branched inflorescence.
In addition, although the species has been well-collected and
distributed to various herbaria for many years, it is unremarkable
and has remained undescribed. This species was first collected in Apr
1938 (Skutch 3765).

Distribution.Crossopetalum enervium is
apparently endemic to Costa Rica, where it is known from both the
northern and southern parts of the country in wet to very wet forest
from ca. 100 to 1700 m elevation (Fig. 2). A
study of shrub and treelet species at Monteverde (Koptur et al.,
1988), includes phenological data about this
species (as C. eucymosum), vouchered by the above cited
Koptur collection (Haber, pers. comm); fruits take about 3 months to
mature and then may remain on the plant up to 5 months. Most
collections are from the northern half of the country in the
Cordilleras de Guanacaste and Tilarán and from the Caribbean
lowlands to the E. A few collections with slightly more prominent
venation, approaching that of C. standleyi, come from
an outlying population in the extreme S of the country on the Pacific
slopes of the Cordillera de Talamanca very close to Panama. Although
not yet known from Panama, this new species must certainly occur
there.

Characterization and relationships. This species is
distinctive for the very faint (when dry) lateral veins and the
delicate, subumbellate inflorescences. In leaf size and certain
aspects of the inflorescence and fruit, this species is most like
C. standleyi (Lundell) Lundell (basionym Mygindastandleyi; [Standley68938, istotype F!]), from
which it differs by its wider and slightly shorter leaves, markedly
obscure venation, and the subumbellate cymes with relatively long
primary peduncles. Both C. standleyi and C.
enervium have obovate fruits and short anther filaments.
Crossopetalumenervium is also similar to the type of
C.riparium (Lundell1476, F!) in its
smallish leaves and delicate, glabrous inflorescences. The
inflorescences of the latter species, however, are more distinctly
branched, and its leaves dry brownish (rather than gray-green), and
are less serrate and more prominently nerved than those of C.
enervium. The stamens are nearly sessile on the type of
C. riparium. Both C. riparium and
C. standleyi (originally described from Guatemala) are
restricted to northern Central American. That the close relatives of
this new species are from N of Costa Rica is to be expected; the
genus is basically Central American and West Indian, with only one
species reported from South America (Gentry,
1993). One collection of C.
enervium, Chávez543, has slightly
puberulent inflorescences.

Among Costa Rican Crossopetalum, the new species is most
similar to C. gomezii Lundell, which differs by having
much larger leaves with very prominent venation. It has been confused
with the most common Costa Rican species, formerly known as C.
eucymosum (Loesener & Pittier) Lundell, here considered a
synonym of the older C. parviflorum (Hemsley)
Lundell:

Crossopetalumparviflorum has much larger, more
open, pubescent inflorescences, larger flowers with longer stamens,
and leaves that dry brownish instead of gray and have more obvious
secondary venation. The five Costa Rican species of
Crossopetalum can be distinguished by the following key:

Etymology and history. The epithet "enervium" is chosen in
reference to the inconspicuous lateral venation of the leaves in dry
specimens. Here again "reconditum" was a serious contender for the
honors; this rarely collected species has actually been in
collections for quite long, the earliest known gathering being that
of AustinSmith1902, in 1939. That collection
and others, including the type, were distributed as
Crossopetalumeucymosum, wherein the new species has,
until now, remained hidden.

Acknowledgements. I thank Michael Grayum for his ever
careful reading of an early draft of the mss, two anonymous reviewers
for further refinements, Silvia Troyo for the line drawings, and Henk
van der Werff for fine tuning the latin descriptions. The photographs
of Gymnosporia haberiana and Maytenus recondita were
supplied by William Haber. Field work resulting in many of the
collections here cited was supported by various National Geographic
Society grants to William Haber and to Michael Grayum and by National
Science Foundation (NSF) grant BSR-8700068 to M. H. Grayum and the
author. Publication was supported by NSF grant DEB-9300814 to the
author and M. H. Grayum.

Literature cited

Gentry, A. H. 1993. A Field Guide to the
Families and Genera of Woody Plants of Northwest South America
(Colombia, Ecuador and Peru). Conservation International,
Washington, DC. 1--895.